In Lightning Forms, you have the ability to create more than one New, Edit or Display customized form by clicking the relevant + sign in the Lightning Forms menu. However, the initial New, Edit, and Display customized forms are the primary default. The default forms cannot be changed. Any additional forms created are non-default.
You can access the non-default forms from any page via a link. To obtain a direct link to the secondary form, click the secondary form's Edit Customization button, scroll to the end of the URL, and change "DesignMode=true" to "DesignMode=false". Copy and paste this updated URL in a different browser tab, and you should see your secondary form.
If it suits your scenario, you can also add this secondary form's URL as an Open Web Page action button on the original default first form.